I think there's little doubt that cabin air can get contaminated. AIUI the real dispute is whether those incidents have caused the serious health issues that have been experienced by some crew members, or whether those health issues have been caused by other things.
Those who are campaigning on the basis of the former (and who may be right) are very good at making sure that the issue is periodically in the headlines. Although I don't have access to that Sunday Times article, the word "emerged" suggests that this may be another episode of that. I thought that the fact that there's a significant number of claims against airlines was already known and reported. (I leave aside the cynical thought that the journalist has used the phrase "it emerged" as a synonym for "I have just discovered".)